Techniques for analyzing the combustion of many materials for hydrogen cyanide have been described. In accordance with one such technique as described in a report by D. A. Reilly, a continuous analysis of combustion gas is made for hydrogen cyanide (HCN) to enable one to study the combustion of polyurethane foams and the like, (see a report entitled "The Analysis of Combustion Gases: Development of a Continuous Analyzer For Hydrogen Cyanide" by D. A. Reilly, ICI Report No. 82392, February 1976).
As described in the aforementioned report, a gas stream containing hydrogen cyanide is passed through an absorption cell through which a hydrogen cyanide absorbing liquid reagent such as an alkaline aqueous solution of sodium picrate is passed. The exposed sodium picrate reagent with any absorbed hydrogen cyanide is subsequently heated to develop a color. The density of the color of the reagent is determined in a spectrophotometer to determine and measure the absorbed hydrogen cyanide.
Although the described technique detects and measures the presence of hydrogen cyanide in a continuous manner, the technique as described has a slow response time and tends to exhibit undesirable fluctuations.